--- layout: "intro" page_title: "Basic Two-Tier AWS Architecture" sidebar_current: "examples-aws" --- # Basic Two-Tier AWS Architecture This provides a template for running a simple two-tier architecture on Amazon Web services. The basic premise is you have stateless app servers running behind an ELB serving traffic. To simplify the example, this intentionally ignores deploying and getting your application onto the servers. However, you could do so either via [provisioners](/docs/provisioners/index.html) and a configuration management tool, or by pre-baking configured AMIs with [Packer](http://www.packer.io). After you run `terraform apply` on this configuration, it will automatically output the DNS address of the ELB. After your instance registers, this should respond with the default nginx web page. The configuration file contains comments describing each resource. ## Command ``` terraform apply \ -var 'aws_access_key=YOUR_ACCESS_KEY' \ -var 'aws_secret_key=YOUR_SECRET_KEY' \ -var 'key_path=/path/to/key/pair.pem' \ -var 'key_name=keypair-name' ``` ## Configuration ``` variable "aws_access_key" {} variable "aws_secret_key" {} variable "key_path" {} variable "key_name" {} variable "aws_region" { default = "us-west-2" } # Ubuntu Precise 12.04 LTS (x64) variable "aws_amis" { default = { eu-west-1 = "ami-b1cf19c6" us-east-1 = "ami-de7ab6b6" us-west-1 = "ami-3f75767a" us-west-2 = "ami-21f78e11" } } # Specify the provider and access details provider "aws" { access_key = "${var.aws_access_key}" secret_key = "${var.aws_secret_key}" region = "${var.aws_region}" } # Our default security group to access # the instances over SSH and HTTP resource "aws_security_group" "default" { name = "terraform_example" description = "Used in the terraform" # SSH access from anywhere ingress { from_port = 22 to_port = 22 protocol = "tcp" cidr_blocks = ["0.0.0.0/0"] } # HTTP access from anywhere ingress { from_port = 80 to_port = 80 protocol = "tcp" cidr_blocks = ["0.0.0.0/0"] } } resource "aws_elb" "web" { name = "terraform-example-elb" # The same availability zone as our instance availability_zones = ["${aws_instance.web.availability_zone}"] listener { instance_port = 80 instance_protocol = "http" lb_port = 80 lb_protocol = "http" } # The instance is registered automatically instances = ["${aws_instance.web.id}"] } resource "aws_instance" "web" { # The connection block tells our provisioner how to # communicate with the resource (instance) connection { # The default username for our AMI user = "ubuntu" # The path to your keyfile key_file = "${var.key_path}" } instance_type = "m1.small" # Lookup the correct AMI based on the region # we specified ami = "${lookup(var.aws_amis, var.aws_region)}" # The name of our SSH keypair you've created and downloaded # from the AWS console. # # https://console.aws.amazon.com/ec2/v2/home?region=us-west-2#KeyPairs: # key_name = "${var.key_name}" # Our Security group to allow HTTP and SSH access security_groups = ["${aws_security_group.default.name}"] # We run a remote provisioner on the instance after creating it. # In this case, we just install nginx and start it. By default, # this should be on port 80 provisioner "remote-exec" { inline = [ "sudo apt-get -y update", "sudo apt-get -y install nginx", "sudo service nginx start" ] } } output "address" { value = "${aws_elb.web.dns_name}" } ```